textproduct: Rapid City

KEY MESSAGES

- Elevated to near-critial fire weather through the weekend - Strong winds possible later tonight into Sunday as cold fronts slice through the area - Moisture-starved active weather next week as northwest flow oscillates baroclinic zone over the northern Plains

DISCUSSION

(Today Through Friday) Issued at 216 AM MST Sat Jan 17 2026

09z surface analysis had weakening low near the Mackinac Bridge with a cold front exiting the CWA. Compact high behind it from MT into central Canada. Water vapour loop showed upper low over IA with shortwave exiting the CWA. Regional radar loop had some leftover flurries over southwest SD associated with stratocumulus rotating through per nighttime RGB loop. Looking upstream, next disturbance to affect us over northern BC/AB.

Today, surface anticyclone slips through northeast WY/western SD with robust warm air advection behind it. How much of that reaches the ground during the day is questionable, so confidence in MaxT this afternoon is less than normal.

Tonight/Sunday, 2 compact shortwaves will race south from Canada into the northern Plains dropping a couple of cold fronts through the CWA later tonight into Sunday. First cold front associated with 2-4mb/3hr pressure rises/modest cold air advection/40-60kt lowest 2km of the troposphere arrives overnight. Mixing ahead of cold front likely to make many calendar day high temperatures occur overnight tonight. Second cold front arrives Sunday with 3-5mb/3hr pressure rises and similar lowest 2km forecast soundings. Good recipe for high winds, so have hoisted a High Wind Watch to account. HREF seems to underplay (as it did yesterday) peak wind gusts with NBM giving 50-80% chance of >50kt wind gusts, especially from K2WX-KRAP. Interesting tidbit (and why the High Wind Watch starts at 18/03z) is a 6mb pressure gradient and 50kt boundary layer wind across the Black Hills suggesting downslope enhancement from Spearfish to Sturgis ahead of the first cold front. Moisture will be limited with this system, but can't rule out some light snow, especially for the northern Black Hills. Temperatures will be near guidance.

Next week looks active, but given surface trajectories, systems will be moisture-starved as they race from Canada into the northern Plains. The baroclinic zone in place will oscillate with frequent bouts of wind and temperature variation (at least 20F probabilistic spreads by the end of the week).

AVIATION

(For the 06Z TAFS Through 06Z Saturday Night) Issued At 1035 PM MST Fri Jan 16 2026

NW winds will continue to decrease through the overnight hours. A band of snow showers is crossing the Black Hills area through southwest SD. This will bring temporarily high wind gusts over 50kt and localized MVFR/IFR VSBY. These showers will continue southward over the next few hours, exiting the southern SD border by 08-09z. VFR conditions are otherwise expected through the forecast period. Strong NW winds are expected to return Saturday night.

FIRE WEATHER

Issued At 216 AM MST Sat Jan 17 2026

Very dry air will be in place over the area today as winds diminish this afternoon. Minimum relative humidities will drop to 10-30% (except 30s over south-central SD). Took at hard look at Red Flag Warning issuance over far southwestern South Dakota, but the joint probability of RH<15%/wind gusts>25mph for 3+ hours is low. A couple of cold fronts then arrive tonight/Sunday with wind gusts from 40-70 MPH possible, particularly over the western SD plains. Both features will lead to elevated to near-critical fire weather conditions for this weekend.

Looking ahead to next week, the pattern changes very little so be prepared for fluctuating temperatures and windy periods. Eventually, colder weather may be more sustained by next weekend, but even then probabilistic temperature spreads increase to 30F leading to low confidence in eventual outcome.

UNR WATCHES/WARNINGS/ADVISORIES

SD...High Wind Watch from this evening through Sunday afternoon for SDZ001-002-012-013-025-072-073-078. High Wind Watch from late tonight through Sunday afternoon for SDZ014-026-030>032-042-043-074. High Wind Watch from Sunday morning through Sunday afternoon for SDZ027-041-075. WY...High Wind Watch from this evening through Sunday afternoon for WYZ060.